The present invention relates to an extract obtained from Rehmannia glutinosa plant having a safener activity to a herbicide paraquat, a safener composition and a method of using the same.
The paraquat uses as a herbicide withers almost all of the green plants non-selectively. When the paraquat is spread on weeds, target farm crops also are damaged by phytotoxicity because of its non-selective characteristics.
In farm cultivation, enormous time and effort are required to control the weeds. In large scale cultivation, usually herbicides are used for weed control. Herbicides can be classified in a selective herbicide which attacks weeds selectively without causing serious damage on crops and a non-selective herbicide which attacks all of the plants in the area where the herbicide is spread. However, excellent selective herbicides are rarely exist and most of the herbicides are non-selective type. Herbicides also could be classified in a soil residual type herbicide and a foliage spray type herbicide according to the spray method. Soil residual type herbicides are used before the germination of the weeds, and thus are less harmful to, plant. However, these are relatively expensive and weeds control efficacy decreases in line with the growth of weeds. Foliage spray type herbicides are relatively cheap, however selective foliage spray herbicide has never been reported yet.
As an outstanding non-selective herbicide, the paraquat is the foliage spray type herbicide which may wither most of the green plants in such a short time of about two days. The paraquat withers the plants by directly inhibiting from the metabolism of cells through formation of superoxide anion in their body. The paraquat is used globally due to its strong weeds control efficacy, however, its use spectrum is considerably restricted due to its non-selective characteristic.
"Safener" is a general term of products designed and prepared for easy use of herbicides through reducing or preventing phytotoxicity of the crops which providing sufficient weed control effects.
Of course, this concept can be applied to insecticides or fungicides. In fact, however, most of the cases are for herbicides. The paraquat--the outstanding foliar spray type non-selective herbicide is used world widely due to its strong weeds control efficacy, however, its use spectrum is considerably restricted due to its non-selective characteristic.
Accordingly, if a safener showing excellent effect to the paraquat is provided, time and effort for weed control could be considerably lightened.
To provide sufficient plant protection performance, it is required that the safener has excellent penetration and translocation capability when it is foliar sprayed. In addition, spreading, wetting, sticking and rain-fastening characteristics is also to be excellent so that the safener may not be lost or degradated at the surface of the leaves for a sufficient time.
The paraquat withers most of the green plants, but certain weeds were found to have resistance to the paraquat.
A medicinal plant, Rehmannia glutinosa is reported to have a resistance on the paraquat in Korean Journal of Weed Science vol. 12, No. 4, pp 374-379, with the title of "Resistance of the medicinal plant Jiwhang (Rehmannia glutinosa) on paraquat."
After perceiving the specific resistance of Rehmannia glutinosa on the paraquat and studying on using Rehmannia glutinosa extract as a safener on the paraquat, the present inventor has obtained Rehmannia glutinosa extract having good safener activity to the paraquat and found that components such as stachyose have the safener activity to the paraquat after purifying the extract.